Always drop lxc_net bridge configuration
Always drop lxc_net bridge configuration

This patch makes sure that the lxc_net play does always write the
LXC bridge-interface configuration regardless of it's admin state.
This is particular important after we deactivate the lxc-net
systemd script as part of the LXC network configuration.

Closes-Bug: #1507795
Change-Id: I9547fe02e20e8d1690340e1193b2453997ada25c

bunchc/openstack-ansible,yanyao/newton,open-switch/infra_openstack-ansible,stackforge/os-ansible-deployment,openstack/openstack-ansible,git-harry/os-ansible-deployment,robb-romans/openstack-ansible,open-switch/infra_openstack-ansible,BjoernT/os-ansible-deployment,weezer/openstack-ansible,major/os-ansible-deployment,yanyao/newton,BjoernT/os-ansible-deployment,yanyao/openstack-deployment-liberty,BjoernT/openstack-ansible,yanyao/openstack-ansible,major/openstack-ansible,jpmontez/os-ansible-deployment,git-harry/os-ansible-deployment,mancdaz/openstack-ansible,jpmontez/os-ansible-deployment,Logan2211/openstack-ansible,bunchc/openstack-ansible,robb-romans/openstack-ansible,open-switch/infra_openstack-ansible,jpmontez/openstack-ansible,mrda/openstack-ansible,mrda/openstack-ansible,major/openstack-ansible,weezer/openstack-ansible,yanyao/openstack-deployment-liberty,Logan2211/openstack-ansible,jpmontez/openstack-ansible,yanyao/openstack-ansible,yanyao/openstack-deployment-liberty,jpmontez/os-ansible-deployment,jpmontez/openstack-ansible,os-cloud/os-ansible-deployment,major/os-ansible-deployment,cloudnull/os-ansible-deployment,mrda/openstack-ansible,openstack/openstack-ansible,BjoernT/os-ansible-deployment,mancdaz/openstack-ansible,cfarquhar/openstack-ansible,stackforge/os-ansible-deployment,git-harry/os-ansible-deployment,os-cloud/os-ansible-deployment,cfarquhar/openstack-ansible,cloudnull/os-ansible-deployment,BjoernT/openstack-ansible